This invention relates to a process and apparatus for chemical sterilization of objects such as medical supplies, instruments and similar articles. More specifically, the invention relates to self-sterilizing packages for housing medical instruments and other sterilizable objects.
Many of the medical supplies and surgical instruments used in an operating room or examination room are reusable. These supplies may include such things as clamps, scalpel blade handles, retractors, forceps, scissors, towels, and surgical garments.
Such items must be collected following each medical procedure, cleaned, and sterilized before they can be used again. To this end, the materials are prepared for sterilization by placing them into various packages including rigid trays, flexible pouches, and other common sterilizable packaging. If flexible pouches are used, the instruments or other objects are enclosed within a pouch that will be sealed around the materials. The pouch may be constructed from various materials that are permeable to a sterilizing medium so as to permit a medium such as a sterilizing vapor or gas to pervade through the pouch and sterilize the enclosed materials. If trays or other more rigid packaging is employed, such structures may be covered with a sterilization wrap and then sealed so that the materials to be sterilized are sealed within the wrapped enclosure. Like the pouches, the sterilization wrap will be permeable to a sterilizing medium. In addition to providing a holder in which to contain and sterilize the medical materials, such sterilization wraps and pouches also provide a transportable, protective barrier against contaminants following sterilization.
Typically, sterilization of medical supplies makes use of a dedicated facility and equipment to supply an external sterilant, or sterilizing medium, which may often be in the form of pressurized steam or ethylene oxide. The sterilant permeates a pouch, wrap, or other enclosure material, or is pumped into the interior of the package, and sterilizes the contents held therein. Following sterilization, the pouch or wrapping maintains the sterility of the respective contents during subsequent handling and transport of the package and contents. Thereafter, the package may be opened using aseptic techniques to access the package contents.
A description of one such sterilization process utilizing sterilization wrap materials is disclosed in U.S. Pat. No. 5,688,476 to Bourne et al. which is owned by the assignee of the present invention and which is incorporated herein by reference in its entirety. Various pouches into which articles may be enclosed for sterilization in either a wrapped or an unwrapped state are shown in U.S. Pat. Nos. 4,121,714 to Daly et al. 4,206,844 to Thukamoto et al., 5,344,017 to Wittrock, and 5,620,656 to Wensky et al. Such pouches may employ indicators which visually signal that the package has been subjected to a sterilization protocol. However, such pouches have been adapted for being subjected to an eternally-supplied sterilizing agent, such as ethylene oxide, that must penetrate the pouch to bring about internal sterilizing conditions within the pouch or other compartment.
In addition, there is growing concern over worker exposure to certain chemical sterilizing agents such as ethylene oxide. Thus, the development of other sterilizing agents would be beneficial. One alternative sterilizing agent is chlorine dioxide (ClO2). This particular sterilant gas is a strong oxidizer and acts as a broad spectrum biocide for bacteria, fungi, viruses, and algae. The efficacy of chlorine dioxide is similar to that of ethylene oxide. In particular, chlorine dioxide is effective at killing bacterial spores. Chlorine dioxide has a high affinity for water which contributes to its ability to kill water-containing microorganisms. However, chlorine dioxide does not have the carcinogenic properties of ethylene oxide.
Additionally, U.S. Pat. No. 3,704,096 to Verses et al. teaches the use of ozone as an internally-contained sterilizing agent. Verses et al. provides a sterilizable package in which an ozone sterilizing mist is introduced to the package followed by sealing of the package. Verses et al. requires tumbling or other agitation of the package to achieve adequate sterilization.
Accordingly, there remains a need for a reliable sterilization system which does not require dedicated equipment or personnel. Further, there remains a need for a sterilization system in which the sterilizing conditions are supplied from within the interior of a sealed sterilization pouch or other sterilization container. Such a system would offer an option to existing chemical and steam sterilization procedures. Further, the system would provide for increased mobility, field use, and as a back-up system for existing protocols which rely upon an external supply of sterilant.
As will be seen from the description and illustrations to follow, none of the above-identified references disclose or anticipate the present invention.
The present invention is directed to a sterilization compartment or package that is capable of being xe2x80x9cself-sterilizedxe2x80x9d. xe2x80x9cSelf-sterilizedxe2x80x9d and xe2x80x9cself-sterilizablexe2x80x9d as used herein refers to packages that have the capability of bringing about sterilization conditions inside an enclosed container without the necessity of being treated with an externally-supplied sterilizing medium. In fact, in certain embodiments, the boundaries of the enclosed container are formed from a substantially fluid-impermeable material so that the sterilization conditions can be maintained within the container for a period of time. These self-sterilizable packages may be desirable for use in health-care facilities that do not have high capacity, large volume sterilization systems. Such large volume systems typically require workers trained to operate the sterilization equipment and require capital expenditures to acquire and maintain the equipment. Self-sterilizable packages provide an attractive alternative for small volume users who may be unwilling to devote the space or resources required for using a typical autoclave or chemical sterilization system. Even beyond the expense aspect, self-sterilizable packaging provides advantages to those who do have the resources to employ large volume sterilization systems. For example, such self-sterilizable packages would require less energy for sterilization, require less handling of the package which influences the propensity for breaching the sterilized conditions, etc.
The present invention recognizes and addresses some of the limitations of prior art sterilization processes and apparatuses. A useful self-sterilizing system can be provided by employing a container having an interior and a sealable opening through which an object may be placed into the interior of the container. A sterilant generator, such as a solid state chemical system that releases chlorine dioxide (although any internal sterilant generator may be employed), is disposed within the container. The container is also equipped with an indicator adapted to indicate when sterilizing conditions have been achieved within the container after it is sealed and self-sterilization has begun. The indicator may take the form of an indicator that indicates the start of sterilant release or the level of sterilant achieved within the container. In addition, the indicator may be a time indicator that indicates the passage time after sealing of the container or beginning of sterilant release.
In the present process, when an object is placed within the interior of the container, the opening of the container may be sealed. The sterilant generator is then activated to release an effective amount of sterilant within the interior of the container to sterilize the objects therein. The indicator associated with the package will then indicate the presence of sterilizing conditions and/or the passage of time.
One type of useful generator for the present invention releases chlorine dioxide gas. The generator may be activated by an appropriate trigger mechanism such as a humid environment which will initiate the release of a predetermined amount of chlorine dioxide.
A sensor responsive to the released chlorine dioxide may signal the successful release of an effective amount of the sterilant within the container. An additional time indicator may also be used to verify that a predetermined time interval has elapsed since sealing of the container or initial release of the sterilant. The release of sterilant and its presence over a sufficient time interval results in sterilization of the package contents.
The present invention enables various types of materials including tubing, fabrics, endoscopes, devices or materials having extensive lumens and internal cavities, and/or heat sensitive materials to be sterilized. Such materials require a sufficiently long duration of exposure to the chemical sterilizing agent that all portions of the materials are exposed to an effective amount of the sterilant. Accordingly, the combination of a sterilant indicator, which qualitatively reflects the release of a sterilization agent, with a time indicator, which quantitatively indicates a sufficient passage of time, work together to provide verification that sterilization has occurred.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims.